Periodontal Bacteria and Outcomes Following Aneurysmal Subarachnoid Hemorrhage: A Prospective Observational Analysis

<b>Background:</b> Periodontitis has been associated with systemic diseases such as cerebrovascular events. Emerging research highlights the potential role of the microbiome in intracranial aneurysm formation and rupture. <b>Aims:</b> We aimed to explore the associations among periodontal pathogens and the outcomes in patients with aneurysmal subarachnoid hemorrhage (aSAH). <b>Materials and Methods:</b> A total of 43 aSAH patients were enrolled. Clinical probing depth measurement and microbiological culture were performed for all participants. The markers of systemic immune response (IL-6, hsCRP) and brain injury (NSE, S100B) were measured between 24 and 48 h after admission. Development of delayed cerebral ischemia (DCI) as the primary and clinical outcome, based on modified Rankin Scale as secondary endpoints, comprised the chosen metrics. <b>Results:</b> A significant association was observed between patients with periodontal pocket depth PPD ≥ 5 mm (n = 28) and DCI, which developed in 19 patients (<i>p</i> = 0.007). In the subgroup of patients with PPD ≥ 5 mm significant associations were found between certain periodontal pathogens and DCI. Higher hsCRP (<i>p</i> = 0.05), IL-6 (<i>p</i> = 0.037) levels were observed in cases with periodontal pathogens, independent of the depth of the pocket, suggesting systemic inflammation. <b>Conclusions:</b> Elevated hsCRP and IL-6 levels, periodontal pocket depth ≥ 5 mm, and red-complex periodontal pathogens are associated with an increased risk of DCI after aSAH, suggesting a role for periodontal disease-related systemic inflammation in DCI risk stratification.